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Fighting a deadly pig disease

Industry, veterinarians trying to contain PED virus, new to the U.S.

By Greg Cima

Posted Jul. 31, 2013

The pork industry is trying to identify risks and improve biosecurity in response to a deadly viral disease that has infected swine from New York to Colorado.

Dr. Lisa J. Becton, director of swine health information and research for the National Pork Board, said her organization is funding research on the coronavirus that causes porcine epidemic diarrhea and is waiting for analysis of data from a joint epidemiologic investigation by government agencies and nonprofit organizations. In the absence of a vaccine against the virus, the organization is working to prevent its introduction on farms.

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Porcine epidemic diarrhea had been found in 16 states, shown in red, by early July.​

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“There is no known approved vaccine for PEDv in the U.S., so until that comes to fruition, we’re really focusing more on the biosecurity efforts that producers and their veterinarians can take,” she said.

PED, which is present in Europe and Asia, had not been discovered in the U.S. before April. The American Association of Swine Veterinarians announced in early July that the causative coronavirus had been found in 16 states.

Dr. Tom Burkgren, executive director of the AASV, said outbreaks in herds have caused the most deaths among suckling pigs, particularly those less than three weeks old when infected, while older pigs can have a high level of morbidity but lower mortality rate.

Joelle Hayden, a spokeswoman for the Department of Agriculture’s Animal and Plant Health Inspection Service, said the agency was helping analyze data collected by a survey administered by the AASV, but no conclusions were available as of early July. The agency is collaborating with the AASV, industry organizations, diagnostic laboratories, and state and local health organizations to collect epidemiologic information. The agency is particularly interested in identifying infections, determining the route of disease spread, and determining how the disease-causing virus entered the country.

APHIS officials also have announced that the agency was working with the Food and Drug Administration to investigate reports that animal feed could be connected with transmission of the disease.

Dr. Burkgren does not expect investigation of the causative virus will lead to a “smoking gun” that reveals how the virus entered the country, but he hopes it will provide enough clues to form some hypotheses. The nearly simultaneous emergence of the disease-causing virus in Colorado, Iowa, and Ohio raised concerns, he said, adding that the pork industry likely would have greater losses were the viruses that cause foot-and-mouth disease, African swine fever, or classical swine fever to enter the U.S. through the same route as the PED virus.

Dr. Becton said the pork board is studying risk factors on the farms that had PED outbreaks and is waiting for analysis of data from the joint investigation. The pork board also will spend $450,000 on research on the PED virus, how it spreads, its survival in the environment, immunity development in pigs, and development of better tests for the virus.

“We don’t have a lot of solid information on how PED acts, because this is the first time we’ve seen it in the United States,” Dr. Becton said. “We have research from other countries, but we don’t have anything in the U.S. that we can compare to.”

Study of how the coronavirus that causes PED differs from the coronavirus that causes transmissible gastroenteritis, which results in similar clinical signs and is present in the U.S., also will help the pork industry, particularly if it attempts to eradicate PED, Dr. Becton said. APHIS information indicates the coronavirus that causes PED is distinguishable from that of transmissible gastroenteritis only through laboratory tests.

“PED is most serious in neonatal piglets where morbidity and mortality can be 80 to 100 percent,” APHIS information states. “Transmission of PED is fecal-oral; no vector or reservoir has been implicated in its spread.”

But agency information warns that contaminated personnel or equipment may be a route to introduce the virus to a susceptible herd.

It’s unclear whether PED can be eradicated in the U.S., but some farms have been able to establish immunity among pigs through herd exposure to the PED virus, Dr. Burkgren said. Elimination would be more difficult if some farm owners were to choose to live with PED rather than endure the expenses and estimated 12-week process to eliminate it, even though the chronic PED would motivate many to eliminate it, he said.

Dr. Becton said the PED outbreaks also led her organization to encourage farms and veterinarians to share more information that could help the industry see more precisely where diseases are discovered and how they spread, as well as improve overall disease surveillance in the U.S. Some farms have declined to share such data out of confidentiality concerns.

Dr. Burkgren also said that, while use of data from private farms is a sensitive issue, the emergence of PED in the U.S. reinforced the importance of the ability to know where a disease is present. He also said the PED outbreaks showed where regulators and industry could improve communication, information sharing, and cooperation. ​